[A new method for determining mineral content of bones using ultrasound]

With conventional methods radiation exposure is relatively high, due to frequent examinations. For this reason an alternative method for measuring bone mineral content was sought. Like X-rays, sound waves are subject to an exponential law of attenuation. For this reason the attenuation coefficient of the sound waves was used to describe the sound-conducting medium. With the help of this transmission sonographic method thickness dependence and increase in attenuation were shown as a function of increasing calcium apatite concentration using a reference system and also femoral sections of varying thickness. Examination of the reflected portion indicated that for this type of measurement the reflection at the bone is negligible at least in the first approximation. In the case of bone specimens a linear dependence was demonstrated between half-value thickness and mineral content in the area of bone calcium concentrations of 50-300 mg/cm. For practical employment of the method, a number of patients were examined in whom bone-mineral-content fluctuations were to be expected on the basis of their disease and therapy. As the examinations indicate, fluctuations in vivo can be detected with the help of this method.